Optical absorption and emission spectral studies of various phthalocyanine (Pc) molecules in PVA matrix have been reported for the first time. The recorded spectra are analyzed to get the important spectral parameters, such as optical absorption cross-section (σa), emission cross-section (σe), oscillator strength (f), fluorescence bandwidth (Δλ), emission wavelength (λ), radiative decay time (τ) and optical gain (G). Analysis shows that the emission cross-section and optical gain are maximum in the NdHPc2-doped PVA matrix. However, a comparison of the calculated emission parameters with that of borate glass matrix show that they are many times smaller in the present matrix.

This paper presents the optimal design of a surface
mounted permanent-magnet (PM) Brushless direct-current
(BLDC) motor meant for spacecraft applications. The spacecraft
applications requires the choice of a motor with high torque
density, minimum cogging torque, better positional stability and
high torque to inertia ratio. Performance of two types of machine
configurations viz Slotted PMBLDC and Slotless PMBLDC with
Halbach array are compared with the help of analytical and
finite element (FE) methods. It is found that unlike a Slotted
PMBLDC motor, the Slotless type with Halbach array develops
zero cogging torque without reduction in the developed torque.
Moreover, the machine being coreless provides high torque to
inertia ratio and zero magnetic stiction

Description:

Emerging Trends in Electrical and Computer Technology (ICETECT), 2011 International Conference on

In this paper, we study a k-out-of-n system with single server
who provides service to external customers also. The system consists of
two parts:(i) a main queue consisting of customers (failed components of
the k-out-of-n system) and (ii) a pool (of finite capacity M) of external
customers together with an orbit for external customers who find the pool
full. An external customer who finds the pool full on arrival, joins the orbit
with probability
and with probability 1−
leaves the system forever. An
orbital customer, who finds the pool full, at an epoch of repeated attempt,
returns to orbit with probability (< 1) and with probability 1 − leaves
the system forever. We compute the steady state system size probability.
Several performance measures are computed, numerical illustrations are
provided.

This study was undertaken in order to upgrade blends of HDPE and
PP, two of the most widely used standard plastics so as to widen their
application spectrum. Dicumyl peroxide was used as the modifier for the
upgradation. Optimum concentration of dicumyl peroxide required for
modification was detennined by measurement of mechanical, rheological,
thermal and morphological properties. Selected blends were used to prepare
recyclable composites with nylon clothes by compression moulding. The
composites were characterized by measurement of mechanical and thermal
properties. The composites were recycled and the mechanical propertics of
the recycled material were determined.

Description:

Dept.of Polymer Science and Rubber Technology,
Cochin University of Science and technology

Aim: To develop a new medium for enhanced production of biomass of an
aquaculture probiotic Pseudomonas MCCB 103 and its antagonistic phenazine
compound, pyocyanin.
Methods and Results: Carbon and nitrogen sources and growth factors, such as
amino acids and vitamins, were screened initially in a mineral medium for the
biomass and antagonistic compound of Pseudomonas MCCB 103. The selected
ingredients were further optimized using a full-factorial central composite
design of the response surface methodology. The medium optimized as per the
model for biomass contained mannitol (20 g l)1), glycerol (20 g l)1), sodium
chloride (5 g l)1), urea (3Æ3 g l)1) and mineral salts solution (20 ml l)1), and
the one optimized for the antagonistic compound contained mannitol (2 g l)1),
glycerol (20 g l)1), sodium chloride (5Æ1 g l)1), urea (3Æ6 g l)1) and mineral
salts solution (20 ml l)1). Subsequently, the model was validated experimentally
with a biomass increase by 19% and fivefold increase of the antagonistic
compound.
Conclusion: Significant increase in the biomass and antagonistic compound
production could be obtained in the new media.
Significance and Impact of the Study: Media formulation and optimization are
the primary steps involved in bioprocess technology, an attempt not made so
far in the production of aquaculture probiotics

Aim: To develop a new medium for enhanced production of biomass of an
aquaculture probiotic Pseudomonas MCCB 103 and its antagonistic phenazine
compound, pyocyanin.
Methods and Results: Carbon and nitrogen sources and growth factors, such as
amino acids and vitamins, were screened initially in a mineral medium for the
biomass and antagonistic compound of Pseudomonas MCCB 103. The selected
ingredients were further optimized using a full-factorial central composite
design of the response surface methodology. The medium optimized as per the
model for biomass contained mannitol (20 g l)1), glycerol (20 g l)1), sodium
chloride (5 g l)1), urea (3Æ3 g l)1) and mineral salts solution (20 ml l)1), and
the one optimized for the antagonistic compound contained mannitol (2 g l)1),
glycerol (20 g l)1), sodium chloride (5Æ1 g l)1), urea (3Æ6 g l)1) and mineral
salts solution (20 ml l)1). Subsequently, the model was validated experimentally
with a biomass increase by 19% and fivefold increase of the antagonistic
compound.
Conclusion: Significant increase in the biomass and antagonistic compound
production could be obtained in the new media.
Significance and Impact of the Study: Media formulation and optimization are
the primary steps involved in bioprocess technology, an attempt not made so
far in the production of aquaculture probiotics.

This study was undertaken to isolate ligninase-producing white-rot fungi for use in the extraction of fibre from pineapple leaf agriwaste. Fifteen fungal strains were isolated from dead tree trunks and leaf litter. Ligninolytic enzymes (lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac)), were produced by solid-state fermentation (SSF) using pineapple leaves as the substrate. Of the isolated strains, the one showing maximum production of ligninolytic enzymes was identified to be Ganoderma lucidum by 18S ribotyping. Single parameter optimization and response surface methodology of different process variables were carried out for enzyme production. Incubation period, agitation, and Tween-80 were identified to be the most significant variables through Plackett-Burman design. These variables were further optimized by Box-Behnken design. The overall maximum yield of ligninolytic enzymes was achieved by experimental analysis under these optimal conditions. Quantitative lignin analysis of pineapple leaves by Klason lignin method showed significant degradation of lignin by Ganoderma lucidum under SSF

SnS thin films were prepared using automated chemical spray pyrolysis (CSP) technique. Single-phase, p-type,
stoichiometric, SnS films with direct band gap of 1.33 eV and having very high absorption coefficient (N105/cm)
were deposited at substrate temperature of 375 °C. The role of substrate temperature in determining the
optoelectronic and structural properties of SnS films was established and concentration ratios of anionic and
cationic precursor solutions were optimized. n-type SnS samples were also prepared using CSP technique at the
same substrate temperature of 375 °C, which facilitates sequential deposition of SnS homojunction. A
comprehensive analysis of both types of films was done using x-ray diffraction, energy dispersive x-ray analysis,
scanning electron microscopy, atomic force microscopy, optical absorption and electrical measurements.
Deposition temperatures required for growth of other binary sulfide phases of tin such as SnS2, Sn2S3 were also
determined

Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4×5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.

Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4×5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.

Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4 . 5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.

The thesis deals with the preparation and dielectric characterization of
Poly aniline and its analogues in ISM band frequency of 2-4 GHz that includes part
of the microwave region (300 MHz to 300 GHz) of the electromagnetic spectrum
and an initial dielectric study in the high frequency [O.05MHz-13 MHz].
PolyaniIine has been synthesized by an in situ doping reaction under different
temperature and in the presence of inorganic dopants such as HCl H2S04, HN03,
HCl04 and organic dopants such as camphorsulphonic acid [CSA],
toluenesulphonic acid {TSA) and naphthalenesulphonic acid [NSA]. The variation
in dielectric properties with change in reaction temperature, dopants and
frequency has been studied. The effect of codopants and microemulsions on the dielectric properties has also been studied in the ISM band. The ISM band of
frequencies (2-4 GHz) is of great utility in Industrial, Scientific and Medical (ISM)
applications. Microwave heating is a very efficient method of heating dielectric
materials and is extensively used in industrial as well as household heating
applications.

Description:

Department of
Polymer Science and Rubber Technology,Cochin University of Science and
Technology

Two stage processes consisting of precursor preparation by thermal
evaporation followed by chalcogenisation in the required atmosphere is
found to be a feasible technique for the PV materials such as n-Beta In2S3,
p-CulnSe2, p-CulnS2 and p-CuIn(Sel_xSx)2. The growth parameters such as
chalcogenisation temperature and duration of chalcogenisation etc have been
optimised in the present study.Single phase Beta-In2S3 thin films can be obtained by sulfurising the indium
films above 300°C for 45 minutes. Low sulfurisation temperatures required
prolonged annealing after the sulfurisation to obtain single phase Beta-1n2S3,
which resulted in high material loss. The maximum band gap of 2.58 eV was
obtained for the nearly stoichiometric Beta-In2S3 film which was sulfurised at
350°C. This wider band gap, n type Beta-In2S3 can be used as an alternative to
toxic CdS as window layer in photovoltaics .The systematic study on the structural optical and electrical properties of
CuInSe2 films by varying the process parameters such as the duration of
selenization and the selenization temperature led to the conclusion that for
the growth of single-phase CuInSe2, the optimum selenization temperature is
350°C and duration is 3 hours. The presence of some binary phases in films
for shorter selenization period and lower selenization temperature may be
due to the incomplete reaction and indium loss. Optical band gap energy of
1.05 eV obtained for the films under the optimum condition.In order to obtain a closer match to the solar spectrum it is desirable to
increase the band gap of the CulnSe2 by a few meV . Further research
works were carried out to produce graded band gap CuIn(Se,S)2 absorber
films by incorporation of sulfur into CuInSe2. It was observed that when the
CulnSe2 prepared by two stage process were post annealed in sulfur atmosphere, the sulfur may be occupying the interstitial positions or forming
a CuInS2 phase along with CuInSe2 phase. The sulfur treatment during the
selenization process OfCu11 ln9 precursors resulted in Culn (Se,S)2 thin films.
A band gap of 1.38 eV was obtained for the CuIn(Se,S)2.The optimised thin films n-beta 1n2S3, p-CulnSe2 and p-Culn(Sel-xSx)2 can be
used for fabrication of polycrystalline solar cells.

Files in this item: 1

The optimum growth requirements of two nitrifying consortia developed from treated sewage by enrichment technique
were determined by a series of experiments. There was total inhibition of nitrification at above 2.75 g r' NH/- Nand 2.5g r'
N02' - N and the ammonia oxidizing consortium preferred a pH at 8.5 and the nitrite oxidizing consortium a pH of 7.5 as the
optima for nitrification. Optimum temperatures were between 20° and 30°C for both the groups. As the rate of airnow was
increased from I to 7 Ilmin, the build-up of N02- -N increased 10-fold and the consumption of N02- -N increased by a factor
of 28.8 implying that the ammonia oxidizing consortium in a bioreactor required three times more aeration than that for
nitrite oxidizers for ex pressing their full nitrifying potential. These data directly contribute for developing a fermentati on
process for the mass production of nitrifiers as well as for designing bio reactors for nitrifying sewage.

Files in this item: 1

Ajitha, S; Dr.Sugunan, S(Cochin University of Science and Technology, September , 2008)

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Abstract:

Mesoporous materials are of great interest to the materials community because of their potential applications for catalysis,separation of large molecules,medical implants,semiconductors,magnetoelectric devices.The thesis entitled 'Ordered Mesoporous Silica as supports for immobilization of Biocatalyst' presents how the pore size can be tuned without the loss in ordered structure for the entrapment of an industially important biocatalyst-amylase.Immobilization of enzymes on ordered mesoporous material has triggered new ooportunities for stabilizing enzymes with improved intrinsic and operational stabilities.

Description:

Department of Applied Chemistry,
Cochin University of Science and Technology

Files in this item: 1

Catalysis is a technologically important field which determines the quality of life in future. Catalyst research in pharmaceutical industry,fine chemical synthesis and emission control demands supported catalysts in bulk quantities.In the present work it was observed that clay supported catalysts mentioned in various chapters could also be used for the synthesis of similar molecules. The K10Ti catalyst can be used for the synthesis similar substituted imidazole derivatives under solvent free conditions and synthetically important Mannich bases of substrates containing various substitutes.Al-pillared saponite can be used for acetalation of other polyhydroxy compounds like glycerol,mannitol etc.Cu-Pd KSF catalyst has found application in C-C bond forming reactions which can be applied to other reactions and similar methods can be adopted for the synthesis of other catalyst by changing the transition metals. Montmorillonite K10 catalysed synthesis of triarylpyridines can be extended to the synthesis tetrasubstuted pyroles.K10Ti can also be utilized for the synthesis of similar heterocycles.